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Can this helicopter/wrecking ball combo remain airborne?
I just ran into this meta-answer which includes this image:

My initial guess is that the wrecking ball is far too heavy for the helicopter to lift, but I'd be interested in the numbers to see just by how much.

From this silhouette, can the make/model of helicopter be determined?  (I'm hoping this image is based of some real-life craft)
If so, presumably the vehicle length is known, and the diameter of the wrecking ball may be calculated (spikes may be ignored) according to the scale of this image
Assume the wrecking ball is solid mild steel with a density of 7.85 g/cm³.  The mass of the wrecking ball can then be calculated
If the make/model is known, then presumably the max payload weight is also known, and we can see if staying aloft is a possibility or not.

Close-voters: I asked this question on Aviation.SE because the key piece of information I was missing was the identification of the craft in the cartoon image.  I think aircraft-identification is on-topic here.

Even if the ball can be lifted I can be more worried about it's swing nasty effects on the fly not to say the catastrophic (for the helicopter) effect of it hitting the ground

Wrecking balls are not usually solid steel - it's much cheaper to fill them with concrete instead.

You know that's photoshopped, right? Quite apart from anything else, wrecking balls don't have spikes.

Slightly relevant, and involving a 500 lb piano: https://www.collectorsweekly.com/articles/at-the-first-rock-festival-pianos-fell-from-the-sky/ TL;DR; the swaying of the mass under the helicopter caused control issues for the pilot. 500 lbs.

Existing answers give analysis on "helicopter lifting a metal sphere of this apparent size", but if you're also interested in whether a helicopter with a dangling wrecking ball is possible/useful at all then it reportedly actually happens.

@DavidRicherby Yes - I was under no illusions that is anything more than a cartoon.  My suspicion that the helicopter is based off a real-life model seems to be vindicated though.

@Kamil Drakari: But from the picture, we don't know that it's a ball at all.  Could be a flat piece of sheet metal...

I knew I'd seen that demotivational poster before...

Less of a "wrecking ball" and more of a morningstar flail, I'd say.

@jamesqf of course it's impossible to say for sure, but the spike placement, angles, and lengths strongly suggest it's a ball.

Amazed that nobody yet has suggested it would work fine if Miley Cyrus were involved.

We don't know what that object is made of. It could be made out of cardboard or Styrofoam for all we know.

@CarlWitthoft Perhaps the two people in silhouette are naked, and one of them is Miley Cyrus?

EDIT
Huge apologies to one and all, in my first version of this answer I mistyped 184 as 84, and then proceeded to do all my calculations based on that.  This is the corrected version.
Also, huge thanks for all the up-votes and comments. I'm so glad it's not just me that is enjoying this question immensely.

The radius of the ball in the image is 21 pixels. The length of the fuselage is 184 pixels, which is 50' 7.5" (15.43m) according to widely available statistics. Hence, a pixel represents approximately 84mm
So, the radius of the ball is 21 x 84 = 1764mm = 1.764m
And the volume of the ball (if solid) is 23.0 m³.
For it to be liftable by the helicopter, using Pilothead's quote of 9000lb (4082kg), the density would need to be 177.5 kg/m³. Mild steel, at 7,850kg/m³, is way too heavy. Expanded polystyrene has a density of 28-45kg/m³, so that would be feasible.
However, if the ball were not solid, and were made of mild steel, the total volume of steel permissible would be 0.52m³. At an outer radius of 1.764m the inner radius must be at least 1.750m to keep the volume of metal down to 0.52m³, so the ball would only be 14mm thick (9/16") and would only cost about $3,300.
So, let's try Titanium (darling of the aircraft industry). With a density of 4,506kg/m³, we could have a volume of 0.90m³. That would allow a thickness of 24mm (15/16"). However, the price of that much titanium would be $229,500 (today's prices - 6 years ago, it would have been over a million US dollars).
Aluminium, however, has a density of 2,700kg/m³. So now we could have a volume of 1.51m³, allowing a thickness of 40mm (1 9/16"), and would only cost $9,360
Pumice, at 250kg/m³, would allow a volume of 16.33m³, allowing a thickness of nearly 0.6m (23½"). That would be very sturdy, I reckon. I can't find a price for a solid lump of pumice that size though.
Incidentally, the people in the picture are also about 21 pixels tall, making them around 1.76m (5'9") tall.
This has now taken up about 3 hours of my time, which like all other hours up to now, are hours I'm never going to get back.  However, it has been so much fun.
FURTHER EDIT
Following a suggestion from Jules in the comments, I've discovered Lithopore 75-150, which is a ridiculously low density foamed concrete.  This could give us the magical solid sphere that we want, with sufficient strength to squish multiple personnel without significant damage to itself.  At the 75 kg/m³ end of the range, we could possibly even have some spikes, and a non-negligible cable mass too.
More maths and engineering research required.....

Or the photo is completely real, the ball is made of marshmallow, and the people are just twice as close to the camera as the helicopter!

Marshmallow, alas, is still way too dense at about 500kg/m³.  I do like the idea of the people being closer though, and being completely unrelated to the helicopter situation.

I tend to doubt that an 8mm thick sheet of aluminum would be "flimsy" according to most people's definition of the word.  Certainly it would be adequate for squishing soft-ish things like a couple of fleeing giants.

I'm guessing you are quite active on physics and or math SE sites, as this whole question would have been better suited there.

No, I'm just an amateur mathematician/physicist (and professional programmer) - not up to their standards, by a long chalk!
I was just having a look at the Mi-26 though, and with its external payload limit of 20,000kg, the Aluminium ball could be 38mm (1½") thick.  That would certainly squish the fleeing giants with negligible damage to itself; especially at its top speed of 159 knots!

The ball is not made of steel or marshmallow. The caption makes it clear: it is rock. Don’t say this to gravity.

Hmmm, Emil, you may have a point.  I'll assume it's Pumice (a volcanic rock) at a density of 250kg/m³ (half that of marshmallow, and a mere 9.26% of the density of Aluminium). As it's impossible to cast pumice, you could find a lump of it, machine it down to a sphere of 3.86m radius, cut it in half, then machine out the inside of each to leave two hemispheres of 9cm (3½") thickness, then somehow join them back together.  You would then have a 9000lb ball of rock.

@EmilJeřábek No, it can't be rock.  Paper beats rock.  It must be made of scissors!

@aroth But that’s the whole point of the joke, isn’t it? (“In the rule book, paper beats rock, but prove it to my rock.”)

Could be, or could also be in the same vein as Rock, Paper, Scissors ... Flamethrower; invoking a disproportionately large option that beats all of the 'official' options with massive overkill.

You forgot to tell us how thick the cable is that is holding the "rock." To me, it looks like it is almost a foot wide, making it like a suspension bridge cable and, if it was made out of braided steel, too stiff to bend like in the picture (also really heavy).

@BlackThorn I think it's reasonable to assume that it's a hollow tube of spider web, and can therefore be ignored ;)

The last two sentences in this answer are fantastic.

Judging from the math, my guess would be that the wrecking ball is paper.

Wait hang on, I don't think your math is right. The rotor of the helicopter is ~203px in length, and corresponds to a real UH60 rotor length (assuming Pilothead is right) of 16.4m. That's 0.081m/px, so the radius of the ball is 1.69m, making the ball's volume 20.2m^3. Also, this makes the humans 1.7m tall, which is much more reasonable. And, it makes Phil M Jones' suggestion of Pumice viable: 250 kg/m^3 at 20 m^3 is around 5000 kg, within an engineering tolerance of the max takeoff weight (And I made an account just to say this!).

@nneonneo my world just fell apart.  I should have used 184 pixels, not 84 as the fuselage length.  Time to get busy with pen, paper and calculator to try to regain any form of dignity.

legendary answer :D

Pumice may not be castable, but aerated stone-filled polyester resin is, could probably be made with a similar density, and would look pretty similar.

The helicopter would be a UH60 Blackhawk. Max payload on a hook is 9000lb. At your mild steel density this is half a cubic meter, so the picture as you describe is impossible.

Eyeballing it, I'd say the ball diameter is about the same as the height - 5.13m.  Thus ball's volume is ~70m³ and mass is ~555 metric tonnes!  Did I get that right?  Definitely no fly.

Maybe they are cheating and the ball is actually hollow :)

Look at the slack on the rope though!

The helicopter isn't a solid hunk of metal.  Why would the ball be?

@aroth: because that's what the question says it is: "3) Assume the wrecking ball is solid mild steel" If we can say its a helium filled mylar balloon then the question becomes pointless. Or even more pointless :)

Of course the photo is absolutely real. I know a guy who knows a guy who says he met the guy in front!

3) Assume the wrecking ball is solid mild steel with a density of 7.85 g/cm3.

That's where you went wrong. The angle of the line and the drag equation allow us to determine the ball's mass, given a known velocity. The ball presents a frontal area of 11.6 m2, which at 80 m/s, a high estimate for the helicopter's speed with an external load, would create ~18 kN of drag. Call it 20 with the spikes.
The cable is angled 35 degrees off vertical, which means the horizontal force on the line is approximately 0.7 times the vertical force. That indicates the vertical force to be approximately 28.5 kN, and thus the ball to weigh ~2,800 kg.
This results in force on the hook of about 42 kN.
So, the load is well within the UH-60's capabilities, and the ball's density at 240 m^3 volume is a mere 11.65 kg/m^3. Still quite an impact even with the kinds of foam available at these densities, though!
For a ball of solid steel (Fv~=20 MN) to deflect that much, the "helicopter" would have to be doing something in the range of 3,000 m/s, depending on the ball's exact Reynolds number.

the total force in the angled case is greater, not less.  The vertical force being reduced doesn't lighten the load on the helicopter.

Yes. The actual load on the hook is (Fh^2+Fv^2)^0.5, or about 42 kN. But a force of more than 1 g is already accounted for in its design. The angle of the line allows us to determine the ball's mass, given a known velocity. At a lower velocity, the ball would be lighter. For a ball of solid steel (Fv=20 MN) to deflect that much, the "helicopter" would have to be well over Mach 10. [edit: Added to the answer]

Ohhhh I completely misunderstood the argument you were making.  The edit helps.  Thanks!

This is assuming stable flight.  The line might be angled because the helicopter maneuvered to catch it's target.

That would take a longer calculation. The ball's got gravity to do some catching up of its own - helicopters can't accelerate so fast as for the image to work with arbitrary mass.

We need a helicopter with steel ball simulator.

The angle of the ball is not that useful an indicator of its mass as it represents both drag and acceleration. The curvature of the chain may be more telling; if you can estimate the mass per unit length of the chain, you can get the tension.

It is possible that at the moment the photo was taken (or created, at least), that the helicopter and the ball were both stationary, albeit momentarily in the case of the ball.  One key aspect of wrecking ball usage is that it swings.  You don't just fly by at 80m/s and hope to take out your target on the first pass. At least I don't :-)

But then, helicopters have limited acceleration, don't just lunge forward like a top fuel. If we had figures, we could account for that version. Although it's really sufficient to demonstrate just one way the picture could work.

Indeed helicopter/wrecking ball combo exists and do some useful job, check this video.

The film shows how the Norwegian Public Road Administration cleared a potential rockfall debris prior to establishing an additional rockfall barrier fence.

First they smash the cliff with a wrecking ball, then drop water over the same area using a water bucket.

I'll note they use a significantly smaller ball. Looks to be about 1m to 1.5m in diameter.

@Schwern Yep, something like that. Anyway the task still very dangerous, especially when the rock must be smashed somewhere int the middle of the height and the rope is not long enough for helicopter to be above the cliff.

@Schwern - Yeah, small but heavy for sure. I think they said the ball was 1,800 kg (about 4,000 pounds), so almost half the (9,000 pound) max load of the helicopter depicted in the question.

If the ball is empty inside, it can probably be made even larger than the helicopter. ZMC-2 was a balloon made of metal, light enough to fly on its own. It even has some rudders that resemble the spikes of the pictured ball. It is probably possible to adjust the lift of the balloon slightly below its weight, so that a helicopter could "lift" it up.
ZMC-2 was made of Alclad, the aluminium alloy.

Even if the wrecking ball is within the payload capacity of the helicopter, a problem will remain.
The big issue with any sling loads is oscillation. A load that swings through an arc exerts a load on the helicopter that pulls the helicopter off the horizontal. If the swing angle is big enough, you'll lose enough lift to lose control and crash. So pilots are careful to keep the load in a stable position.
A wrecking ball is the antithesis of this: it only works when it's swinging. So instead of the 9000 lb quoted above for the maximum load, the ball has to be much lighter to make sure you can keep flying when the ball swings around.

As Therac discusses, the ball has a manageable mass.  Now as to concern about speed, those calculations assume static forward flight, and it is likely this ball is being swung all around. That could account for the slack in the lines.
As far as stabilization, we can take a cue from the other people who control swinging loads from high above them: those who load/unload container ships, dropping the container right on the pins of the lower container or the haulaway truck or train.  Their rule is simple: Always stay above the load. If you are at position X and it is at position Y, X - Y becomes new impulse to make it swing.  You don't want to do that except to cancel out existing swing, and even then you have to be "in phase" (or to be more precise, not).
Of course in the wrecking ball business, you'd want to swing it.  But it'd take careful management (especially post-strike!) to make sure the cable didn't jerk the helicopter in unexpected directions and cause an areodynamic upset, or throw debris at the helicopter. Even dust repeatedly getting into the turbine could be a problem.

Of course it's photoshopped, but I think this is meant to depict a mine, not a wrecking ball.
Per wikipedia, "Floating mines typically have a mass of around 200 kg, including 80 kg of explosives" - see https://en.wikipedia.org/wiki/Naval_mine. That's well within the carrying capacity of a Blackhawk.

The image is fake.  There are no known slingloads for the UH-60 which correspond to the image shown.

Fake? Are you sure??? Maybe it's a concept demo by the 160th - they do wild stuff like this, don't they?  :-)

Not to mention the stability and CG havoc being played if that thing was to swing as depicted.  This answer is a reasonable frame challenge, since the question is based on utter nonsense.  As an answer, though, it could use a bit more meat to spell out why the situation is absurd.


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What are the major non-pilot causes of GA accidents?
I'm considering getting a private pilot license. From what I've read, pilot error is the leading cause of major airline crashes -- such as on this page, but that's for major commercial carriers. As the pilot, pilot error is something that I can address myself. One of the things that concerns me is the chance for an accident due to circumstances beyond my control.
What's the cause breakdown for general aviation accidents? What are the most common mechanical failures?

For a statistical overview of General Aviation accidents I suggest checking out the Joseph T. Nall Report prepared by the AOPA Air Safety Institute. Everything I'm citing below comes from the most recent report (the 23rd report, covering 2011).
The leading causes of accidents in 2011 were:

Pilot Error - About 77%
This includes poor flight planning, weather encounters, and a host of other things that we could at least theoretically avoid if we actually did the things we were taught to do in training.
Mechanical or Maintenance related - About 13%
This includes engine failures, control system problems, landing gear failures, etc.

The largest chunk of mechanical failures are "powerplant failures", which account for 38% of the mechanical failures, or a bit under 5% of total accidents.

Everything Else - About 10%
This includes freak occurrences like a flight instructor "walking into a moving propeller" (I kid you not, it's in the report!). A large chunk of these are also engine failure for causes that could not be determined.

If we add all the engine/powerplant failures together (the explainable ones from "Mechanical" plus the unexplained ones from "Everything Else") they come out to be  11.5% of total accidents, and are statistically the number two cause of Non-Commercial General Aviation accidents after "Pilot Error".

The Nall report is fascinating reading. I ran across references before but they were dead links.

@AndrewS There are lots of other great resources on accidents if you poke around on the ASI site - the Nall report is pretty much the canonical compilation of that data though. Sadly not all of the years are available online, but also-sadly the reports are very similar year-to-year...

I wonder how many of those mechanical errors can be attributed to poor maintenance though.

@JayCarr The way the Nall report is structured "maintenance-related failures" (ones caused by doing maintenance - either improperly or properly - and causing other stuff to break) and "maintenance-deferral failures" (caused by not doing maintenance) wind up in the same bucket - the concept of "provocative maintenance" is one that can be well applied to aviation though...

Here is a good analysis that is a bit dated but should be relevant.
The data is from 1985-1995, 160,000 planes and 20,000,000 flight hours
Accident causes:
Pilot related: 80%
Mechanical/maintenance: 16%
Other: 2%
Unknown: 2%
The focus is mainly on pilot error (which is an interesting read). The breakdown of the mechanical/maintenance issues is as follows:
Engine/Prop: 70%
Gear/Brakes: 15%
Oil system: 5%
Controls/airframe: 2%
Fuel System: 3%
Electrical/Ignition: 3%
Vacuum Sys/Instruments: 2%
The NTSB has a lot of data available either in reports or by database query. The reports only break mechanical issues down to powerplant/non-powerplant. During 2007-2009 it was about 80% powerplant, 20% non-powerplant for personal flying. Other types of flying had various distributions. If you consider oil and fuel as powerplant systems, then it's about the same as the data above.
Anecdotally, from reading through many GA accident reports where maintenance was a factor, a lot of things come up after a maintenance visit. Things not attached properly/securely, not done correctly. So having good maintenance, and doing a very thorough check afterwards, will help.

Additionally for many mechanical failures the outcome depends on how good emergency plan the pilot has.

These are both great answers but I can only accept one... please leave this one up!

My experience as a long time pilot and mechanic I have seen engine failures caused by accessories or other components external to the actual internal powerplant. If the powerplant is repaired or overhauled properly according to manufacturers recommendations and all the parts are approved and within tolerance the power plant can be expected to last until TBO. External components often fail much sooner than TBO. Items such as exhaust baffles blocking exhaust outlet, Magneto failure, starter drive coming apart, vacuum pump attachment failure, fuel pump failure, fuel injection or carburation problem, alternator failure and the list can go on. Preventive maintenance and detailed inspections can prevent failures.

Good reminder that "engine failures" aren't always limited to just the engine itself. Welcome to Av.SE!

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Do tanker aircraft distribute their own fuel?
Do tanker aircraft, (such as the KC-135, KC-10, S-3B, etc), distribute fuel from their own fuel tanks, or is it strictly from a separate cargo tank?
Obviously, some cargo tanks are going to be involved, as an aircraft carrying only the fuel in it's wing tanks isn't going to be a whole lot, and some of these aircraft are known to fuel some very thirsty birds, such as B-52's, etc.
Sub question: What proportion volume of the aircraft's fuselage is taken up by the addidional fuel. Do they just pack it as full as they can with fuel? Seems like this would very quickly add to weight, and you would struggle getting such a fuel laden bird off the ground.

Don't get too concerned about the fuel weight, as it is part of the aircraft design to accomodate that.  Consider a KC-10 can carry 356k lbs with all of its tanks full, while a Boeing 747-8I can carry 315k lbs of fuel and takeoff at a total weight of 987 k lbs.

@casey for a refueling mission a 747 wouldn't have other payload. Max fuel capacity is 239,000 L hence 239000L0.81kg/L2.2 gives 425,898 lbs. much heavier than MTOW minus MZFW

Both the KC-135 and KC-10 can burn the fuel it carries on board for refueling (the notable exception was the KC-135Q, which carried separate tanks of JP-7 for the SR-71 Blackbird).

Both indeed do have significant fuselage tanks - the KC-10 is notable for being 'dual-mission' capable, meaning it can carry both fuel and cargo, and the KC-10 is also air-refuelable (so a KC-135 can offload extra gas into a KC-10 when their crew rest is up, allowing the KC-10 to stay on station and refuel other planes longer). The maximum fuel load of a KC-10 is 356,000 pounds. This is over 7 full loads of gas for a B-52 (B-52G and H could carry 308,000lbs of fuel, so 365,000 capacity of KC-10 would potentially fully fuel a B-52 one time, with enough fuel left to get the KC-10 home. Of course the B-52 would never be completely empty in the air so the KC-10 would not need to offload the full 308,000lbs), or 30 full loads for an F-16 with external tanks, and the maximum fuel load of a KC-135 is 200,000 pounds, or over 4 full loads of gas for a B-52.
As for how much of the fuselage is taken up by fuel tanks, you can look at cutaways of the KC-135 and KC-10 (unfortunately the captions for the KC-10 are in a foreign language, as I could not find a high-enough resolution one in English). In both cases, the fuel tanks are in the lower half of the fuselage - the reason the KC-10 has a cargo mission as well is because it is a larger aircraft and has a much higher gross weight. The KC-135's cargo space is much smaller, and as such is not used for transporting large items. This technical document for the KC-10 also gives volume of each tank (called Fuel Cells):

Forward Fuselage - 8,250 gallons in 3 sections, 6' deep
Aft Fuselage - 9,870 gallons in 4 sections, 6' deep

You are correct that it is a struggle getting them airborne when fully loaded - several of the KC-135 pilots I have talked to have taken until the very end of 10,000 foot plus runways to get airborne, and one of the KC-10 pilots I know said they would occasionally take off with less than a full load then take on fuel from a KC-135 to make it easier.
Page 3-45 of this technical manual has a chart for calculating minimum runway for a particular speed - for example, a sea level takeoff at 30 degrees (Celsius) at Max takeoff weight would require about a 13,500 foot runway.

Wow, this is exactly what I was looking for. I hadn't realized the KC-10 was actually larger than the KC-135! Must be some nice engines!

I would almost suggest JATO bottles for takeoff, but something about strapping a few rocket engines onto a plane carrying nothing but fuel seems like a bad idea...

@HCBPshenanigans - the KC-10 has 3 engines producing 52,500 pounds each while the KC-135R (currently flown model) has 4 engines producing 21,600 pounds each - the old E-model engines only produced 13,750 pounds each, so you can see why the old 135s especially were underpowered

At McConnell AFB they have 8 KC-135s that can also take on fuel (we called them R/Ts).  Also, the KC-135 can carry 80,000 lbs of cargo for various missions.  (I was a boom operator during the enlisted portion of my AF career.)  A fully loaded 135 with the CFM-56 engines can outclimb a KC-10 any day of the week! ;)

I don't entirely get why air-refueling of tanker aircraft makes sense - can anyone explain?

@sanchises - if a jets crew has the end of their duty day, but still have gas, then they can offload it so the gas can stay on station but they dont have to

@SSumner Thanks, I interpreted the sentence the other way round, which did not make sense. Got it now, though.

@Sanchises aircraft can be limited at take off by their Maximum Takeoff Weight, but actually fly with more weight (particularly so if the tanker is departing a base with a shorter runway) - so for particularly long tanker missions you can load the aircraft to the MTOW and then top it up to the mission load from another tanker once its in the air.

@Airhead: Probably still less bad than strapping them onto a plane packed to the gills with high explosives...

"This is over 7 full loads of gas for a B-52 ... so 365,000 capacity of KC-10 would potentially fully fuel a B-52 one time". Quite the contradiction right there in just one sentence! :)

@Sanchises That would make an interesting Question!

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How exactly should I understand the term "accidental hull loss"?
How can the IATA claim that the year 2015 saw no accidental hull losses, if we had the Germanwings Flight 9525 accident? Even if this one is not considered "an accident" then there are a few others (for instance Metrojet Flight 9268) that can be clearly taken as "accidental hull losses".
How should I understand "accidental hull loss" exactly, or what is it that I am missing?
EDIT: While I agree, that I may be missing some certain points and the general definition given in IATA article and while I agree with all answers and comments given here, I think that on contrary Carson Air Flight 66 fits pretty perfectly into "accidental hull loss" definition. It is from 2015 and it is a bit interesting, why IATA "forgot" about it in their report?

Metrojet 9268 is explicitly listed in the link as being deliberate.

This is an interesting question and doesn't deserve negative votes. The terminology used in the industry is not always clear, and certainly not used accurately or consistently in reports, especially in the general media. The official terminology and definitions are not all perfectly obvious to me either.

@DanieleProcida I didn't downvote and I agree that official terminology can be confusing. However, the ordinary English meaning of the word "accident" is something that is non-deliberate, and the asker seems to be aware of this in their suggestion that Germanwings 9525 might not be counted as accidental. It does seem pretty clear that neither a pilot deliberately flying a plane into the ground nor a terrorist blowing up a plane is an accident.

It's also worth remembering that aviation reports are released (internationally) in English. Those who are not native English speakers may question their understanding of a word they thought they knew when they see it used in a context that doesn't jive with their understanding, while native English speakers will more readily pick up meanings from context.

@trejder - add that into the original question as an example - it will get more attention there than here in the comments.

Re. Carson Air, the IATA infographic says there were zero hull losses "involving passenger fatalities" and the Carson Air flight was cargo only.

@Pondlife Funny thing... If we exclude non-jet, non-accidental and non-passenger flights, that crashed, then we really had 2015 "safer then ever" year in aviation. The question is, is there still any reasoning in talking about safety in this perspective?

Both the MetroJet and GermanWings incidents were deliberate acts of destruction, not accidents in any common understanding of the word, or indeed in the sense defined by the Convention on International Civil Aviation.
The Chicago Convention, as it's also known, defines an accident as:

An occurrence associated with the operation of an aircraft [...] in which  [...] a person is fatally or seriously injured [...] except when the injuries are [...] inflicted by other persons.

My emphasis added - see Annexe 13 of the Convention for the full definition - it's quite dry but interesting, if you're interested in that kind of thing. The exceptions it lists are illuminating.
Deliberate acts and "incidents"
I do think that the definitions in the Annexe are slightly odd. You'd think that the deliberate destruction of an airliner in flight should be called an incident, but an incident is apparently:

An occurrence, other than an accident, [affecting safety].

I guess that's one way of describing a bombing or deliberate crash into terrain... but then there's also a Serious incident which is merely:

An incident involving circumstances indicating that an accident nearly occurred. [my emphasis again]

So that would make the GermanWings and MetroJet cases incidents, but not serious incidents!
However: since "Appendix 7" of the ICAO Accident/Incident Reporting Manual lists "types of incident", and deliberate acts of destruction are not amongst them, I can only deduce that they are classified as neither incidents nor accidents. I am not sure exactly what the official terminology is for them.

It is odd, indeed. I would actually expect accident to include the deliberate acts, because the rules for investigating them, from the ICAO point of view, are the same and have the same purpose of suggesting measures to reduce risk of similar occurrence in future.

@JanHudec The distinction probably comes from a liability standpoint--who to blame. With an accident (non-deliberate) you start looking at the aircraft maker and maintainer. With a deliberate act you start looking at the one who committed the act.

@JanHudec But the very meaning of the word "accident" means non-deliberate.

There are at least three different sets of terminology here: (1) everyday English, as defined in a dictionary and used by the media, (2) "incident" and "accident" as formally defined in the Chicago Convention, and (3) "accidental" as defined in the relevant Insurance policies. Working in the industry, the general rule is that every event is an "incident" (i.e. something that happened must be reported, but without any demonstrated issues either of safety or individual responsibility)  until an investigation has proved that "incident" is the wrong classification.

@JanHudec Also, if an incident occurs in the US the investigation will be carried out by an entirely different agency if it's intentional (FBI) rather than being an accident (NTSB). The FBI would certainly depend heavily on the expertise of the NTSB, but they would still be the agency in charge

@TomMcW, I don't know about US, but generally I was under impression that in the intentional cases there are two, separate investigations. One by the safety board with intent of reducing risk of recurrence of similar event and one by the criminal justice. And the safety board one works the same whether it was criminal act or accident.

@JanHudec: It certainly used to work that way in the U.S. as well (see, for instance, NTSB AAR75-07, about the 1974 bombing of TWA Flight 841).

A deliberate act would be an incident, not an accident, according to the legalese, given that the hull loss is not counted as accidental.

The intention of the Annex 13 wording seems to be that an incident is a sub- accident (incident: something went wrong, serious incident: something went really wrong, accident: something went really wrong and people were badly injured or the aircraft was badly damaged). I don't think it was written to take into account this kind of event.

I think your question actually deserves a second answer, approaching it from another direction. You ask "How can IATA make this claim?"
What is actually being claimed?
In fact, the claim is quite slippery, and you'll notice that it is expressed in multiple different ways, with different meanings, in different reports.
These include:

"no accidental hull losses" (lead-in of IATA's Safer than ever article)
"zero jet hull loss accidents involving passenger fatalities" (the infographic they link to from that page)
"No fatal jet hull losses" (headline of IATA press release)

(They're also written in a way that makes one wonder whether the zero figure only refers to "IATA Operational Safety Audit (IOSA)-registered carriers", though in fact I think that's not the case.)
Then you can read other reports that relate the news as "The number of airline accidents declined in 2015 with no deaths from jet aircraft reported", "Not a single passenger died in a jetliner accident", and so on. No wonder people find it hard to see what is actually being claimed.
The six conditions
But anyway, working from IATA's own texts, the actual point is that in 2015 there were no incidents that were all of the following:

hull-losses (i.e. the aircraft was destroyed or written-off)
accidental (deliberate acts don't count)
involved fatalities...
...of passengers
of jet aircraft
operated by airlines

I'm guessing that if we exclude any one of those conditions the figure will no longer be zero, but I'll leave that for others to show or not.
If there's anything to be concluded from this, it's that words do actually mean things and when they change, so does meaning!

Well, this is a great answer... again! :> The only thing, that I don't understand, is why did you give another answer instead of editing and extending the one you already have here? I think, that's how things works here anyway?

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Is triskaedekiphobia (fear of the number 13) the reason commercial planes normally do not have a row 13?
When I first time heard this "legend" I couldn't believe it. I was really surprised, if not shocked, to actually find row 13 missing on my next passenger flight. (I believe it was a Boeing 737.) Is this really due to superstition about the 13th row? Was it so hard to push aircraft producers to renumber all other seat rows?
I know that people can be absurd about their superstitions. But realistically, the odds that a passenger airplane will crash are minimal. And should it really crash, chances that you'll survive due to being seated in row 12 or 14, as opposed to 13, must be below statistical error.
I find it very difficult to believe that people would choose not to fly simply due to superstition about being seated in row 13. Is there a more rational explanation?
EDIT (after Patrick's answer): I don't know, if I expressed myself enough clearly. I don't think, that people are dumb, because the're worried about number 13. I rather think, that thinking, that row 13 is unlucky, specifically on airplanes (where, in case case of crash all seats mostly are equally unlucky) is a bit weird.

Also the 13 floor, room etc. are typically skipped over but that depends heavily on culture (13 is not bad luck everywhere)

There is also a question on skeptics about the 13th floor in hotels, which mentions aircraft as well

Missing row numbers depend on the specific carrier.  Many have 13.  Some are missing 13.  Some are missing 11.

On almost all the planes I flew both row 13 and 17 were missing. And not to make room for something else.

It's worth noting that skipping 13 when numbering things in general is fairly common in the West. Building floor numbers, for example; especially older buildings. But I don't think it's really superstition at this point, but rather just a tradition.

the number 14 is unlucky in many Eastern countries. There is a software product we use at work that skipped from version 12 to version 15 because of this.(or so the story goes)

I always assumed that 1% of people avoid the number 13, and the other 99% don't care.  So by removing the number 13, they appeal to 100% of customers.

Regarding the edit: I guess the thing with fears like triskaidekaphobia is not that they think that something will happen if anyone sits in row 13 but that they think something might happen if they specifically sit in row 13. So the fear is not about chances of survival but about anything happening (might not even be related to the person themself) if the person sits in row 13.

Naaah,  it's cause I patented "Aircraft Row 13" so they can't use it.

Somewhat related: http://aviation.stackexchange.com/questions/3593/what-happened-to-rows-10-and-11-on-frontiers-a-319

Note that it's largely irrelevant that you were in a Boeing 737. Plane interiors vary significantly between airlines and something as simple as renumbering the seats could be done by any owner of the plane at any time. That would have nothing to do with Boeing and an airline would be likely to apply a policy like "no row 13" to its entire fleet.

@DavidRicherby Who you are referring to? I never expressed, that skipping row 13 has something to do with Boeing company itself. I only mentioned Boeing 737 as my first aircraft, where I observed this fact. But, I don't know (and actually don't care too much), who was responsible for omitting row 13 in case of that plane.

Mentioning the manufacturer suggests that you thought it was relevant. I'm just pointing out that it isn't especially relevant. Much more relevant would be if you said that you first saw it on Airline X, since that airline may well have an explicit, documented policy of not having a row 13 for reasons Y and Z.

Fear of number 13 is known as Triskaidekaphobia.
I randomly entered some flight numbers on SeatGuru and found that this one has row 13 (aircraft is B737):

In this case, there is no 13th row:

However, in this case, several row numbers (12, 13, 14) are skipped to adjust galleys and lavatories. This could be that they were added later or can be removed in future to add more rows.

The bottom line is that regardless of what you name it, there remains a 13th row. If a plane is about to crash (God forbid) I would be worried about being on the plane, rather than just the seat number. There are several studies that safest seats are in the back. So, rows 1-12 may not be as unlucky as row 13.
If you have 12 million dollars and I can give you one million more1, would you not take it?
In several parts of the world 13 is a lucky number.

1Trust me, I will not do it, even if I have that much money.

FWIW, you don't need Triskaidekaphobia for 13 to be a commercially unviable number. You just need the superstition that 13 is unlucky. A phobia is not the same as a superstition. Phobias are more hardcore than that. It's not merely avoiding buying seats on row 13 but more like preferring to die rather than set on a row with number 13.

Also, here in Asia you find building floors and airplane seats with the numeral "4" missing (no row 4 or row 14 or row 24..) since the word for "four" in various Chinese dialects sounds like "death" or "die"

I honestly think in most cases it has less to do with actual fear and far more to do with tradition.  I personally get a bit of a laugh when I get in an elevator that skips the 13th floor.  I like traditions, especially irrational ones (so long as no one is hurt), it helps me remember I belong to a larger group of people :).

@slebetman Same reason there was no Psion Series 4!

Aircraft producers don't choose numbering schemes, it's up to the airline to specify layout, row numbers, lavatory placement, etc. Airlines think about their customer base, and in the western world the occasional person has a fear of the number 13 so some airlines choose to skip the number 13. It costs them little to do so and it shows their good will.
They'll go out of their way to skip the number 13 but they skimp on decent food and legroom. It says something about the industry, doesn't it?

You already said it, it costs them little (very close to nothing). Changing the food or the legroom costs millions. So yeah, it says something about the industry: that they're in it for the money.

Agreed. Row and seat numbering (and even number, width, and type of seats) is purely up to the airlines, not the aircraft manufacturers.

actually, manufacturers offer semi-standard layouts that customers can adapt to their specifications. Many elect to just change the fabric and paint colours and won't bother to change the row number signs as well :)

I just want to point out the irony of the 13 upvotes. That is all.

Yes, the airlines designate the seating numbers, just like they designate the flight numbers. Look how many different airlines have flight 777 to Las Vegas.

@Thebluefish That looks like it has been resolved, instead using the digit 4.

It might also be economical thinking behind it: Many people in the west do not want to sit in row 13, so leaving it completely out makes it one less special wish customers can utter (and therefore one less thing the airline has to care about).
Source: Worked beside my studies at several places. One was a European airline's help-line. They had no. 13 and we had an incredible number of calls of people asking to be re-seated... Not having a 13 solves this problem entirely.
By the way: I find your wording in the question very aggressive towards people with this issue. It sounds like you considered them dumb. In fact it is people of high intelligence who tend to be neurotics of this kind. I had a professor back at the ETH who hated the number 17. He's well-renowned and well-known in his area but wherever he goes, he will never sit on seat 17, in row 17 or reside in room 17 (or even just ending in 17).

indeed, it's often the highly intelligent who have the (in the eyes of others) weirdest quircks.

I don't know, if I expressed myself enough clearly. I don't think, that people are dumb, because the're worried about number 13. I rather think, that thinking, that row 13 is unlucky, specifically on airplanes (where, in case case of crash, all seats mostly are equally unlucky), is a bit weird.

Sorry for my misunderstanding then, I just felt that there was a certain prejudice in the question. In that case I was wrong :)
Anyways: In the case of superstition, logics plays a minor role. I mean, is there really a difference between somebody thinking, that row 13 on the plane is "evil" or somebody having to touch wood before going out? It's the same "logic" behind. In one way or another we all have quirks, some stronger, some weaker. As long as one's daily life is not affected, it can be ignored, otherwise there are therapies.

Consider that in Italy number 17 is also an unlucky number. This is why Alitalia (amongst others) removes both rows 13 and 17.

It's essentially 100% free for an aircraft production team to skip row 13 and go straight from 12 to 14, when numbering. Why would you not do this, and risk upsetting a minority of your paying customers who may have a less enjoyable flight because they are superstitious? It isn't particularly relevant whether you think it's silly: it's a cost-benefit thing.

Agreed. Flying, for many people, is inherently a scary process; putting yourself in the hands of an unknown, unseen group of people, where any serious mishap is more likely to end in disaster than not (whether or not this is true does not change what many continue to believe)... why make an added burden of sitting someone in what that person may believe is an unlucky seat.

As I explained in some comment, I don't think, that being scary for sitting in row 13 is silly. I think, this is silly, because in case of crash you're most likely dead, no matter, in which seat you're sitting. It is not like: I won't bet 13, because it is unlucky for me and I have chance to win, if I bet 14 or 12. It is like: No matter, what I bet, I loose (in case of airplane crash).

@trejder: So what? You're trying to rationalise about irrational fears; that won't work. It's great to hear that you're a perfect being and aren't afraid of anything, but there are over seven billion people in the world and this change to row numbering costs basically nothing.

I have never said, that I'm perfect, nor that I aren't afraid of anything. I have actually never said, that I find this silly. All I was asking, was to find, if there are other reasons for renumbering seats. I'm very happy, that this question is quite famous and brought so much attention and many good quality answers. But, conlusions made out of my question, by people like you, somethimes surprises me.

I don't know about airplanes, but I believe it is the reason why hospitals do not have any room labeled as room 13 on any of their floors. Room 413 on the 4th floor is labeled as room 414.
I can only assume that patients who are already anxious about their illness will reach out for an excuse, no mater how absurd, that might be hindering their recovery, and therefore they result in having Triskaidekaphobia. It is their attempt to find something to blame.
Hospital administrators do not want to be constantly handling complaints and requests from people asking to be moved to another room, so they simply have no room 13 to begin with.


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Where can I find an accurate list of IATA meal codes?
I'm trying to "compile" single list of IATA meal codes. By using different airlines and data sources I have found many meal codes. However, I have also found problems with codes that are used to mean different things, or different codes used to mean the same thing. For example:

On Cathay Pacific's special meal page I have found an information, that both Non-Beef Meal and Liquid Diet Meal are using the same code of SPML. These meal types seems to be far different. How to understand this? A bug on CP's page? To make things more complicated, another source uses SPML code for Special Meal or Specify Meal.
Cathay Pacific uses VGML for Vegetarian Vegan Meal (Strict vegetarian food with high protein, rich iron and high calcium). Other source uses VVML code for this meal type and have VGML code reserved for Vegetarian Non-Dairy Meal. Is there any difference between these two meal types and if yes, then which code is correct / official according to IATA.

Help with the above two examples would be appreciated. However, my main question is:
Where can I find official IATA codes for food?
If there is any "ultimate source", that we can / should use for this purpose (ignoring airline's specific listings, as in case of Cathay Pacific)? If so, then please, provide a link to it.
EDIT: Please, consider above paragraph. This question asks official IATA meal list, not about airline-specific regulations.

I have, of course, contacted Cathay Pacific to ask them the same question as in point one, but received automated response including "one of our team members will contact you within 14 days". I have a small hope, that I get some answer here a bit faster than within two weeks! :>

I'm voting to close this question as off-topic because how airlines code and load food onto their aircraft is not within the scope defined in the help centre.

On point one, I'd guess 'SPML' is effectively a flag saying "it's complicated, check attached paperwork" rather than the actual meal description...

"How airlines code and load food onto their aircraft" is certainly not within the scope of this site. The problem is, that this question asks, where I can find official IATA codes for food. And, no, it does not ask about how airlines load food onto their aircraft. I think, you have a slight problem with your translator / interpreter. Voting to reopen.

This isn't anything that's come from IATA - the airlines choose/use their own codes and they're part of the airlines booking systems. SPML is fairly generic and used by most airlines, but how they store the "details" of this varies between airlines. Some use other codes, others will add remarks to the PNR or attach additional paperwork

I'm voting to close this question again because it's not within the scope defined on our scope page and also because it's about resource location, which is explicitly off-topic for this SE (and most others, too, except [opendata.se] and [softwarerecs.se].) Whether it's from IATA or not, I don't see how being from IATA makes it any more on topic than being from a particular airline. IATA is just an industry trade group of airlines; it is not a regulatory body.

Well, this question is about IATA codes. And it is wrong. It was closed two times. In the light of this, I still wonder, how it is possible, that this question os wrong and all other iata-tagged questions are OK? There is even some kind of dump speculation question about IATA numbers pool running out, which definitely is out of scope here and should be asked on mathematical-like SE site, but... forget it. I'm tired explaining, that my question is valid.


text:
Aborted take off. What happens next?
A rare -- as I was told -- situation of aborted take off for a large passenger jet. What is next?
Everything goes as smudge as possible after getting jetliner to full stop. Plane clears the runway and goes back to the either parking position or designated place at taxi way.
What steps must be performed in order to make this aircraft back to take-off waiting queue?
Approximately how long will it take for this plane  to be taking-off again? I know that this vary on many circumstances that's why I am asking about approximate only. Is there any priority for the plane that should already went off? Will that take minutes, tens of minutes or hours?

Clarification: This question is for the sake of the story that I am writing. It (both story and the question) involves Boeing 777 taking off from LHR in August 2014.
Aborted take of is due to a misleading information coming from cargo doors' sensors that reveal a possible problem only during take-off, not before (i.e. during taxi). The doors are actually closed (no real danger posed after check). But there's a tiny piece of fabrics from cargo loader's uniform stick in between doors. This question is a follow-up or alternate version of this question. Here I'd like to know what happens, if such situation will be detected after V1 or shortly after take-off and thus after such aircraft returns safely to the airport and clears the runway. In linked question I am asking about the same situation detected before V1.
I am aware that most airline experts will say that such situation is not possible at all. I am, on the other hand, a system designer and I know that such "ghost" situations of "neither 0 nor 1" sometimes do happen. But, for the sake of this question, if you feel uncomfortable with such reason -- let's assume that take-off was aborted due to any other reason, i.e. engine failure. I belive that such reason has similar severity as the need of checking whether cargo doors are really closed due to fact that on-board computer provides misleading data.
I'd lilke to underline that this is purely hypothetical question. I am aware that while such questions are sometimes hard to answer, they're in general quite welcomed in this site and are not off-topic.

Let me guess, the detective realizes that the suspect was there based on the "false" detection and the wisp of cloth, and finds the body hidden in the cargo bay? Depending on how you play it this could be a fun story. Good luck!

@MadPhysicist Thank you for your kind comment. The story goes completely other way (there's no body in the cargo :), but I am happy that you liked it.

A lot depends on whether the reject happened during the high energy or low energy phase of the takeoff.  The boundary between the two is the reason for the speed call "xx knots", usually 80 knots or 90 knots, during the takeoff roll.
There will be specific procedures to follow following a reject, depending on the airplane and the airline's own procedures.  Normally the first thing is to bring the airplane to a complete stop on the runway, set the parking brake, and evaluate the situation (you might find something's on fire and you need to order an emergency evacuation right there).  You'll have called reject to ATC when the decision was made, so ATC will expect you to stop and will tell aircraft behind you to abandon the approach (and will likely have dispatched the fire trucks to your location just in case).  Now there are situations where judgement and common sense is applied and if you rejected at the beginning of the roll because a binder fell on the floor and made a big bang but you were only going 40kt, and you realized what it was right away, you might just tell ATC what you are doing and taxi clear.  However with rejects, it's usually assumed the runway is contaminated with FOD and ATC may close it anyway to have a runway inspection done.
As soon as you are satisfied that no evacuation is required and it's safe to taxi, you'll taxi to the ramp.  If it's a low energy reject, and you have a BTMS (Brake Temperature Monitoring System) you can expect to only have to wait for the BTMS indications to get back into the green before going out again.  If the BTMS is inoperative and was deferred under the Minimum Equipment List, you will likely have to consult some QRH  (Quick Reference Handbook) brake cooling time tables to determine how long you have to wait.
If the reject was high energy (above the 80/90 kt speed call), or if the BTMS indications are giving an extreme overheat indication (red) because you rejected after you'd already nearly overheated the brakes while taxiing from riding them, you can expect to be required to have a brake and tire inspection performed before you can go out again.  Rejects close to V1/decision speed are considered high risk maneuvers in the general scheme of things.  In any case, a call to Maintenance Control will be the next thing after getting clear of the runway to figure out what to do.
Brake use by crews during taxi has a big effect on things and prudent brake use is really important.  It's easy to get brake temperatures close to the yellow (or white) range just from riding them constantly to hold the airplane back if it has more thrust at idle than it needs to roll at taxi speed. You have to either let it speed up, apply brakes, then let them off over and over, taxi with one engine, or use idle reverse (which airlines don't like you using because it uses up reverser cycles with a maintenance impact).  The CRJ200 is really bad for this and can can get rolling to pretty high speeds with both engines at idle; it's like driving a car with the idle speed set way too high when you just want it to creep along.

CRJ200 ... interesting. That explains why on some flights (passenger) it felt insanely fast- it WAS. Cool.

It's a bigger problem if you have carbon brakes because they have to be up to a certain temperature or they wear like crazy, so you are always trying to apply them hard or not at all.  If you ride them moderately when taxiing you wear them out in no time if you get them hot but not hot enough.

"Set the brakes" - not in our manual, unless you plan to evacuate. Stationary while you sort things out, yes, but with minimal brake pressure. Otherwise, though, nice answer.

Depends on the operator and the manufacturer I suppose. On the RJ, the OEM's SOP was PB set following a reject.  The brakes are hot one way or the other and it makes no difference to them how hard you are applying them and now that you are stopped they are no longer heating up, so I don't see the point of not doing it.  Too much risk of attention being diverted and relaxing the feet and drifting along unawares.

you rejected at the beginning of the roll because a binder fell on the floor and made a big bang sounds like something out of a movie like "Airplane!" :-D

Once when I was bush flying in 1990 I was taking off in a C-180 on floats in whitecap conditions, and a steel box medical/survival kit strapped to the side of the sheet metal extended baggage compartment came unfastened from the pounding and fell over flat on the floor just as I was lifting clear of the water.   BANG!!!!!!!!!    After I recovered from the heart attack, it seemed to be flying fine and I deduced what had happened, looked back and saw the box lying there, and carried on.

@Michael surely you're joking!

@WayneWerner I am serious. And don't call me Shirley.

"Nervous? Yes! First time? No, I was nervous before" :>

Depends why the takeoff was aborted. Maybe it was a minor technical issue that the pilots can fix right away, in which case they may be allowed to just stay on the runway for a few seconds and then start the takeoff again. Or maybe there was a significant issue with the aircraft, which would require the aircraft to return to the gate to get fixed by a mechanic, which might take minutes, hours or days.
If the takeoff was aborted at high speed, it is likely the pilots will have to wait for the brakes to cool down before attempting another takeoff, which can probably take anywhere from a few minutes to an hour at most.
If the aircraft vacates the runway and is ready for departure again within a few minutes, the pilots will simply inform ATC who will find a spot for the flight in the departure queue.

Fuel might be a problem. A full power take-off run followed by a long taxi back will consume a fair amount of fuel, which would need to be calculated.

Many operators are required to call their company, at minimum to get a new release. They might be able to do it while waiting in line, but they might not. If there is no line, ATC may want to stash them out of others' way, which means more time taxiing to and from that spot.

If it is hot brakes, there is a designated area for the aircraft to taxi to, fire brigade is called, the fire controller is then in charge of the aircraft (not the pilot) and it won't be released until the temperature drops to safe levels (measured with infrared gun), you must not use any fire extinguisher other than dry chemical powder or risk explosion. Danger area is tyre side walls and can extend 100s of meters.

Good answers already, but given the hypothetical clarification in italics, I will just add that after taxiing back to the terminal and discovering that the fault was a small piece of cloth in the sensor, the crew would be in communication with dispatch to amend their clearance, get a new takeoff time, and be released again.  After that, resume ops normal.

Boeings reject takeoffs.  They don't abort.  Abort an engine start, reject a takeoff.
A rejected takeoff in a large airplane is one of the most hazardous things one can do, particularly a high-speed reject.
My last rejected takeoff was a high-speed, and we taxied clear and waited while fire crews monitored the brakes.
The reject is briefed as part of the takeoff briefing; both a low speed, and a high-speed (low speed typically being below 80 knots, and high speed from 80 knots to V1, or decision/refusal speed).  How it is handled depends on the aircraft and company; each pilot will have specific duties during the reject.  The pilot flying may handle the physical operation of the rejected takeoff, or it may be the captain that takes over and rejects the takeoff.  This is typically thrust levers to idle, ground spoilers deployed, RTO autobrakes followed by manual maximum braking, and reverse thrust as appropriate.
The pilot not flying (sometimes called the PNF or non-handling pilot) will apply forward pressure on the control column, note the reject airspeed, contact the tower, and support the flying pilot in clearing the runway, if possible.
Whether a subsequent takeoff is a consideration or not depends on brake energy, the reason for the rejected takeoff, etc.  Typically brakes will need to be cooled, fuel recalculated, the aircraft reconfigured, quite possibly the FMS reprogrammed, perhaps a new clearance obtained, possibly an ammended flight plan, etc.
We have a runway-change checklist which will also be run in the event of a low speed reject.


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Aborted take off due to not closed cargo doors. How this will be signalled?
A hypothetical situation (I know that it is very unlikely to happen in real). When closing cargo doors, a piece of fabric from the luggage carrier's uniform stick in between. The cargo door is actually closed (no real danger), but the latching sensors are sending a misleading signals.
How this will be communicated in the cockpit? What visual or audio signal will be used / emitted in the cockpit to inform the crew about the reason? Is there any specific light or button as an endpoint for cargo doors sensor? Is there any specific sound?
How will the crew communicate to the tower the reason for an aborted take off (what kind of message, who will do this -- flying pilot, non-flying pilot)?
Clarification: This question is for the sake of the story that I am writing. It (both story and the question) involves Boeing 777 taking off from LHR in August 2014.
Aborted take of is due to a misleading information coming from cargo doors' sensors that reveal a possible problem only during take-off, not before (i.e. during taxi). The doors are actually closed (no real danger posed after check). But there's a tiny piece of fabrics from cargo loader's uniform stick in between doors. This question is a follow-up or alternate version of this question. Here I'd like to know what happens, if such situation will be detected before V1. In linked question I am asking about the same situation detected after V1 or shortly after take-off and thus after such aircraft returns safely to the airport and clears the runway.
I am aware that most airline experts will say that such situation is not possible at all. I am, on the other hand, a system designer and I know that such "ghost" situations of "neither 0 nor 1" sometimes do happen. But, for the sake of this question, if you feel uncomfortable with such reason -- let's assume that take-off was aborted due to any other reason, i.e. engine failure. I belive that such reason has similar severity as the need of checking whether cargo doors are really closed due to fact that on-board computer provides misleading data.
I'd lilke to underline that this is purely hypothetical question. I am aware that while such questions are sometimes hard to answer, they're in general quite welcomed in this site and are not off-topic.

"[..] on-board computer performs an emergency brake" There is no such function on any airliner that I know of. BTW, "Brake" and "Break" are two completely different terms and you seem to be using them interchangeably, which one are you wanting to use? A "break" in aircraft terms may mean a hard turn, usually used in a military context, or it could mean something that "breaks".

Also, luggage/cargo doors have very complicated latching mechanisms with sensors. You can't close the handle unless the door is locked in place, and sensors will alert the pilots before they even depart the gate that the door is not latched. Things like United 811 and AA 96 don't really happen anymore.

Question re-edited and made shorter. I think some of your comments may be removed. Please, see if this question is now answerable? Thank you.

This will never happen, doors checked for locked status way before takeoff. Pilot would have to neglect the checklist which is a fundamental part of their procedure for it to ever happen on takeoff. And which aircraft is it? Airbus and Boeing have 2 screens in the centre called ECAM or EICAS where the second screen is configurable. 1st always shows engine info. Second is able to bring up a display of the doors and their locked status. And the central maintenance computer is responsible for showing cautions on the displays mentioned, one of which might be a doors caution.

There have been case(s?) where pilots ignored the checklist. And an open door could be seen by other aircraft or the ATC.

@Craig It seems that you have already answered half of my question. Any fault on cargo door will be reported on EICAS screen. No, I only need to know, if there will be any additional sound and how would the crew inform the tower about reasons for aborted take-off (this particular or any other). Is there any standardised communication here, some kind of codes etc. Or will that be just a free talk ("We have aborted take-off due to error in system X or Y popping on our screens")?

@Craig As for your (and other) doubts. Let me say this again, this is highly hypothetical situation, but since I am IT designer I believe it can happen. In this situation, doors are correctly shut with just a piece of fabrics sticking somewhere around unnoticed. This causes that there is no alert during taxi and only during take-off signals from doors sensors causes to display a warning or error. I am not a pilot, but as a system design I can imagine situation of "neither 1 nor 0, but somewhere between". That's just a electronic devices and IT systems there. Nothing more. Error-prone.

@trejder Interesting story idea. It is possible that someone could have neglected the rigging procedure for the cargo door micro switch so that it is just on the cusp of the 1 or 0 with vibration from takeoff roll making it jump between, or that there was dirty contacts in the switch or some sort of FOD. The visual EICAS caution will always be associated with either a Master Caution or Mather Warning light (depending on the severity of the fault) that the pilot presses to acknowledge the problem and the aural chime for this is also heard over the headset.

@Craig Might want to put that in an Answer, rather than the Comments.

@Craig Thank you for a nice comment. And as nick012000 says, it would be good to craft an answer out of that question.

You will typically get a DOOR OPEN alert displayed on the EICAS system.  A competent crew would have spotted such a discrepancy before pushback.

...and a crew incompetent enough to not notice before pushback would probably be incompetent enough to ignore the warning during the takeoff roll. There are more important things to worry about when rushing down the runway than whether all the doors are properly locked shut.

@FreeMan Even though your comment is 3,5 years old, I am totally shocked of what you have written. Things like explosive decompression or issues like Turkish 981, United 811 and AA 96 and probably many more clearly suggest that you are all wrong. I'd say that there are very little things more important to worry about when rushing down the runway that the fact whether all the doors are probably shut.

It's possible for an indication to appear after the fact; in other words, what wasn't evident prior to pushback and engine start, becomes evident at a later time.  During the takeoff roll, for example.  I can't recall ever rejecting a takeoff for something I knew about before entering the runway: it's something that occurs later.
A piece of fabric in a cargo door wouldn't cause the door to fail, though conceivably it might be possible for an erroneous indication to develop.  Or at least it's plausible enough to be included in a story.  There's certainly far less credible ideas, such as the movie Airport, in which an airliner submerged under the ocean is still producing bleed air from it's flooded engines to pressurize the airplane...or the ubiquitous (and idiotic) trope about airplanes that blow apart when someone fires a shot inside.
For the sake of argument, say that the fabric does cause an error in the door closed indication after the takeoff has begun, is discovered prior to 80 knots, and the takeoff rejected.   The crew may report the reason to air traffic control, but realistically will be notifying ATC that there's a mechanical cause and will be requesting a return to the gate.  The immediate problem may be that the gate is no longer available, if it's been arranged for another flight.  In any event, even with the discovery of fabric, the airline maintenance will not make the assumption that the cause has been discovered, and will inspect the door and door system for other problems.
I had an instance in a much smaller airplane many years ago, in a Learjet 35A, departing Los Angeles (LAX).  A very new captain was in the left seat, and I was in the right.  Passing 80 knots, I got a door light (the  cabin entrance door on the Lear is large and could be very dangerous if opening).  I announced the door light and called for the reject.  The new captain didn't respond.
I knew the door system well enough to glance over my shoulder, note the handle position, and knew that the door couldn't open.  I knew that the sensor for the door was in the handle, sometimes not depressing the microswitch due to interior trim interference.  Short story: I knew the door had to be closed and couldn't open. I also didn't intend to put the flight in jeopardy by attempting to reject or take the airplane from the other pilot...who was clearly zoned out and too focused on the takeoff to hear or respond.
I called V1, rotate, and after we left the ground, positive climb.  When the new captain didn't respond, I announced the gear, raised it, and walked the airplane through the takeoff flows, and clean-up.  The captain was still focused and not listening. When I was done with the checklist, I pointed to the door light and said firmly, "You're aware of the door light?"
For the first time, the captain responded, and to be polite, he freaked out, and attempted a rapid bank.  I took the aircraft from him, and asked what he intended to do.  He said he was going to return to land opposite direction at LAX...bad idea.  I told him we would not, and that we'd continue the departure until above 18,000, when I'd check the door.  I informed him that it was a sensor, that I knew it was a sensor, and that we weren't going to create an emergency over a sensor (the Lear door can't open with the handle forward).  When we were up and clear, I pulled the door trim aside, and pressed the handle down, an the light went out.  We reviewed the checklist, and continued.
A high speed rejected takeoff is one of the most dangerous things you can do in a transport category turbojet aircraft.

Welcome to the society and thank you for an enlightening and detailed comment. I read it through and found it very valuable. However, it does not directly answer the question ("How it will be signalled in the cockpit"), so I cannot accept this one as an accepted answer and only can up-vote it. Thank you.


text:
How does the luggage car's driver at the airport know what to do?
I would like to learn a little bit more about the work of luggage car's drivers.
Specifically -- how do any of them know:

which luggage car to ride next?
which plane must they deliver this particular luggage car to?
which roads must they take in order to avoid dangerous situations (crash with an airplane or other airport support cars)?

If this is not a good place for asking questions like that, is there any procedure or source of information which could help me to answer these questions?

Depends on the airport. But you could also ask how any truck driver anywhere in the world knows where to go, the answer would be similar. Normal procedures for logistics don't disappear just because you are at an airport.

Well... no. I don't think so. I don't think that normal driver has to take care about 20-50 times bigger vehicles that may appear in their way, while at an airport you must be aware of possible colliding with an airplane when you're riding a luggage car. Plus: normal drivers use road signs and traffic lights that you don't see at parking positions and taxi ways at an airport. Do we have any source of information for such extra procedures, including luggage driver's roosters and "how to go around the airport"?

Normal traffic laws also apply at airports! Speed limits, right of way etc. There are road signs, and in some cases traffic lights. There are service roads for vehicles to use, which are marked just lige regular roads. Roads are named, just like normal roads, and there are street addresses/numbers. In addition, vehicles must always yield to aircraft, and yield signs are usually posted in places where service roads cross taxiways.

OK, I see your point. Thanks. But that still makes us talking about last point only. What about two others. Is there any common procedure, same pattern or is this always purely per-airport?

I think you are overthinking this. The airport has a schedule of all the flights. The handling agency has a bunch of baggage handlers. Their manager tells them what to do. The exact details obviously vary from company to company, airport to airport. In the end, it's just a matter of moving goods from point A to point B. No different from any large warehouse, port or shipping company.

Sure thing, thanks. So the next point as, as previously -- whether you find it worth to bring these comments into an answer?

How does a bus or taxi driver know what to do?  How do they know to avoid crashing into things?  How does the ticket agent know what to do?  How do you know how to do your job?  Were you trained?  Probably...

@trejder: Truck drivers may not have to look out for bigger vehicles - barring the occasional train, of course - but they have to look out for lots and lots of small vehicles.  And pedestrians, critters crossing the road, &c.

Thank you for all your comments. This question was aiming more like into: is there any description available out there about how a typical baggage carrier rooster works like, how his tasks are dispatched etc. It seems from all your comments that this is purely per airport. And that's the answer I was expecting. Thank you.


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How much power does the APU generate in a Boeing 737-300?
I have just watched Mayday episode 11, season 11, "Nowhere to Land" about TACA Flight 110 incident and I was more than surprised to learn that:

APU must be turned on,
APU needs about 5-10 minutes to start powering anything,
APU can be used to power lights in the passenger cabin (???).

This is the exact flow of events (plus voice description) as it is shown in above cited episode:

a pilot is shown turning APU's switch,
narrator explains that a certain amount of time must pass before APU starts working,
lights in passenger section are turned on after this period of time passes.

Contrary to the above, I was always told (based on Air Transat Flight 236 incident, shown in season 1, episode 6, "Flying on Empty" of Mayday, and based on other sources):

APU is deployed automatically (gravitational solution) whenever power from engines is lost,
APU starts powering equipment nearly immediately,
APU is able to power basic instruments only, even pilots cabin remains dark, not to mention passenger sections.

What is the reality?

"APU is deployed automatically (gravitational solution)" I think you are talking about a Ram Air Turbine (RAT).

Yes, you'are correct and that makes most of my question not answerable (based on wrong assumptions). But, on the other hand I am more than sure that in Air Transat Flight 236 incident, shown in season 1, episode 6, "Flying on Empty" of Mayday "RAT" is clearly named "APU". Because I have never heard "RAT" name before (until now) and I watched that episode a few years ago.

@trejder "Flying on Empty" of Mayday "RAT" is clearly named "APU"" Don't use dramatic TV episodes to determine real-world things. A RAT is never labeled "APU" in any aircraft.

So is what is the power output of the APU?  How many amps at what corresponding voltages and AC/DC?  How much bleed air is available for Airpacs, etc?

@RonBeyer Good to know that my memory is still working... somewhat. I watched "Flying on Empty" years ago and when the whole APU-mixed-with-RAT discussion started here I wasn't that sure. But you confirm that they a clear mistake.

"5-10 minutes" before the APU can supply power? Not at all. The start cycle is more like 20-30 seconds, after which it can supply electrical power to most of the aircraft systems.

You are getting the APU mixed up with the RAT:

The Auxiliary Power Unit (APU) is an engine powered generator, either a gas turbine or a piston engine. APUs deliver enough power to start engines, power cabin lights,  cockpit instruments and radios, and in some cases power hydraulics. Often the APU can only be run at lower altitudes where the air is thicker
A Ram Air Turbine (RAT) is a small, automatically deployed propellor run generator which is lowered into the airflow if there is a loss of power. The RAT generates enough power for the most critical systems only, and is designed to give pilots enough electricity to glide until the APU can be started

Often the APU runs from the same fuel supply as the engines, so if the airplane runs out of fuel the APU is unavailable, so the RAT is all they'd have.

There are piston "APU's" for ground vehicles, but I've never heard of a piston APU for an aircraft, do you have an example?

Nothing recent comes to mind @RonBeyer, some older aircraft like the DC-3 had an optional piston engine APU. Since some are still in service it made sense to include it.

The 737-300 APU can provide electrical power up to FL350, so the comment about "at lower altitudes" isn't entirely accurate, at least in this case. Also, the 737 doesn't have a RAT.


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Does a stalled wing exhibit no circulation?
If a wing is stalled, will the wing not exhibit any circulation as predicted by the Kutta-Joukowski theorem?
If yes, then how would this affect the pressure distribution between the top and bottom portions of the wings?  Would the top portion of the wing (low pressure) carry most of the lift?

If there is no circulation, there would be no lift. In reality, circulation stops to increase linearly when the angle of attack nears the stall range and drops beyond stall. However, there is plenty of lift left beyond stall.

180° polar for several NACA 4-digit airfoils, from Hoerners Fluid Dynamic Lift.

how would this affect the pressure distribution […]?

Think of the stalled airfoil as of an entity which comprises the airfoil itself, the boundary layer around it and the separated flow in its wake. This will still have nearly-inviscid flow around it, and the wake will make it "look" to the outer flow like an airfoil with a lower angle of attack and a really drawn-out pressure recovery. There is still a suction peak at the nose, albeit much weaker than for the clean airfoil in attached flow, and constant suction past the separation point. On the bottom, however, flow is almost unchanged except for a region near the trailing edge where the low pressure in the wake speeds up the local flow.

Would the top portion of the wing (low pressure) carry most of the lift?

The answer to the question on which side more lift is created depends a lot on how lift is interpreted. In the end, lift is the difference between the pressures on the bottom and the top sides, and cannot meaningfully be split into a top or bottom contribution. What can be done is to compare the pressure on one side with static pressure, which will yield a side-specific lift fraction. But then you can arbitrarily compare surface pressures with any pressure level found inside the wing box - it will cancel out once you calculate total lift.


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What do these instruments do?
This is sort of the reverse of an aircraft-identifcation question.
I am attempting to build a virtual model of a Gee Bee R1 (for fun). Unfortunately I haven't had much luck finding plans or images of the inside of an R1 cockpit. The best I could find is this image of a miniature model of a R2 instrument panel:

And this still from a video about a modern-day flying replica (also an R2):

Having desperately reached as far as the second page of google images without success, I've given up trying to find anything better. But if anyone knows some better sources, please let me know!
With very limited actual knowledge about any sort of aircraft, I have no idea which doohickeys do what. So my actual question is, can anyone identify what each of these things likely indicates or does?

if you make a zoom of the instruments showing the units we can provide you better support.

@TrebiaProject. Unfortunately that's the best I could find. The original source has some closeups, but only of a few parts of the model :/

Well... in the link you are showing you can see that there is a bigger picture showing that one is air speed and the other shows altitude as you guessed.

Are you seeking to identify all instruments on the panel, or only the ones that you have highlighted? You have correctly identified everything you have so far labeled.

@JonathanWalters All of them, or as many as possible. Given the seeming nonavailability of good sources I'll have to accept what I can get :)

@mins Thanks, but if I'm not mistaken those are all images of the Gee Bee model Z

For the panel image that you provided, I should be able to identify all major instruments:

A: Magnetic Compass - Pretty self explanatory. Note that in the real aircraft, A and K may have been switched.
B: Vertical Speed Indicator (VSI) - Indicates vertical speed, either up or down, in feet per minute.
C: Engine Tachometer - Indicates engine revolutions per minute (RPM)
D: Sensitive Altimeter - Indicates feet above Mean Sea Level (MSL). Adjustable for atmospheric pressure via Kollsman knob.
E: Air Speed Indicator - Measures indicated air speed, most likely given in MPH for this vintage aircraft.
F: Artificial Horizon - Gyro instrument giving an indication of an artificial horizon; shows pitch and bank variations.
G: Amp and Volt Meter - Amps are indicated on the left, volts on the right.
H: Oil Pressure and Temperature Gauge - Oil pressure is indicated on the left, in PSI, and Temperature is indicated on the right, in °C.
I: Clock - Probably an "8-Day", spring driven, hand wound device.
J: Magneto Switch - Control for ignition systems. This control only shows three detents. There should probably be four detents: Off, L, R, and Both (L and R refer to Left and Right magnetos).
K: Directional Gyro with Inclinometer - The bottom part is the Inclinometer (ball), indicates coordination and skid or slip. The top part is the Directional Gyro. Note that in the real aircraft, K and A may have been switched.
The inscription reading "NR2100" is indeed the aircraft registration, typically used as part of the aircraft callsign.
The knob below A is likely used to set the gyro compass (K) that should be in that location.
The knob below F is likely to adjust the pitch indication on the artificial horizon (F).
The red knob between F and E is probably meant to be a knob to cage the artificial horizon (F) and should actually be placed in the location of the screw directly above and left of that red knob. See the Bee Gee Z panel I linked to below.
The knob between E and D is probably meant to be a larger knob that might be part of a pull control. I have no real idea of what it is, but my guesses would start with carb heat, primer, starter engagement pull knob. Could be many other possible functions.
Reference the photos in this album by Roger Ritter depicting a Bee Gee Model Z. I understand that it is not the same model that you are looking for, but the cockpit layout is very similar, and should be informative. His photos helped me confirm the identification of the gauges in the panel image you provided. Photo album linked only, due to image copyrights.

Wow, thanks! Unless/until a better source image is found this is good enough for me. Just curious, do you have a source for the swapping of A and K? And do you have any wild guesses at what some of the various knobs and switches might do? (this page has some closeups of what appears to be a different version of the same model; some of the knobs are in different places)

@gandalf3 See the additional information I added to my answer. My assessment of switching A and K is due to what the gauges appear to be, the placement in the Bee Gee Z panel I linked to, and the location of the adjustment knob found under A.

My guess on that missing 4th detent for the Magneto Switch is that it is currently underneath the switch itself - Probably the "Off" setting.

@DarrelHoffman That's a good guess, and you might be right. However, the original Scintilla mag switch found in the BGZ was not so configured.

I'll defer to your expertise.  I'm no pilot, but I'm a programmer who's worked in aircraft simulation, so I've spent a lot of time staring at blurry photos of cockpit instruments trying to figure out stuff like this.

@DarrelHoffman Though not a programmer, I've spent my fair share of time doing that as well, in a past life; I know what that's like. Not sure I'm an expert on this, but I have had my hands on real magnetos and switches for quite a few years.

If your answer is accurate, then the pointy thingy immediately below and to the left of D should be the Kolsman adjustment knob, no?

@michael Yes, the smaller knob is the Kolsman knob. Do not confuse the larger knob between E and D for the Kolsman knob.

@JonathanWalters Indeed.

Either "directional gyro" or "heading indicator" may be more appropriate terms for what you are calling a "gyrocompass"..  "Gyrocompass" may sometimes be used to refer to a gyroscopic instrument that is automatically slaved to a magnetic compass.  It is also used to refer to an instrument that finds the direction of north without reference to a magnetic compass at all -- see https://en.wikipedia.org/wiki/Gyrocompass .  Neither of those things are what we are looking at here on this control panel.PS I'm really surprised that a race plane would have an artificial horizon / attitude indicator.

@quietflyer that's a good point. I may have based that nomenclature off of pictures of an old gyro, but I think the model term Directional Gyro is more accurate regardless of how the original part may have been labeled.


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What liability concerns would drive an airplane homebuilder to scrap their plane?
Via this post by Ron Rapp, I found this video of a plane owner and builder dismantling a GA plane and then scrapping the airframe. The video claims this is because

after consulting with aviation attorneys and other experts regarding builder's liability, the owner concluded there was only one way out.

However, I'm completely in the dark about - and rather baffled by - what this liability risk would be, and how it relates to the Van's Aircraft lawsuit. What liability would a builder pilot be under in the event of a crash that they would be able to avoid if the plane were factory-produced?

The simple answer is the guy was going to sell (or perhaps give away) the aircraft.  Of course, they then have liability.

@JoeBlow op knows that, they're asking what the difference in liability is between an individual and a company.

See this last article of a series on EAA site (links to other articles at the end). The problem is the liability related to third parties that may be difficult to dismiss in a waiver or disclaimer which binds only the buyer and the seller.

@mins Thanks for that link. I find it all crazy (surely if I buy a homebuilt aircraft I ought to be aware that all aircraft are dangerous and I need to take all steps possible to minimise the risk, and if I decide to take on passengers then it's my responsibility to make sure they're safe, including making sure the plane is airworthy) but at least it's more reasonably inscribed in (what an outsider might call) the overall craziness of the US legal system.

I understand that the aircraft owner had sought for some time to donate the aircraft. I would presume that he had come to a time in life where he was, or felt he was, no longer able to fly the aircraft, and so was seeking to rid himself of what may have become a burden (hangar fees, etc.).
To quote liberally from the builder/destroyer's daughter who created and uploaded the YouTube video (this is quoted from what she wrote in the video description):

It took him two years to make this decision about his plane. He did actually try to donate it to a couple of aviation schools in the area and the schools politely refused the offer. He also tried to donate to a local museum and was also refused.
He knew when he built the plane he might face this decision one day, but he hoped some of the laws would have changed by that time.
[...]
Mr. Ron Rapp, author of the article “A Tragic Pile of Twisted Metal” and noted blogger on his website The House of Rapp., highlights many reasons my Dad made this decision among others.
A couple months before my dad made his final decision, a local fellow pilot was named in a lawsuit because he sold the plane he built to a man that later crashed and killed himself in the plane. The spouse of the buyer filed the suit and also named other companies who made parts used to build the plane.
Many have commented that he should have used a limited liability entity, such as a LLC or a corporation to sell the plane. However, because the plane was not, at the time of manufacturing, owned in a properly capitalized limited liability entity with a legitimate business purpose and was, in fact, used purely for personal reason, courts would in almost all cases “pierce the corporate veil.” Therefore, this does not offer adequate (or any) protection.

I don't think I can add a whole lot to that. Apparently, he had decided that he was unwilling to take on the liability of letting someone else fly what he had built. In the absence of a party interested in the aircraft for anything other than flight, he chose to destroy it.

In the terms of selling (or giving away) the aircraft, couldn't a document be signed which releases him from liability? But I suppose he couldn't find anybody willing to take that risk.

I doubt such a document could be drafted that would truly hold up in court.

You're probably right, otherwise people might try to take advantage of being able to do so with (knowingly) faulty creations... it's too bad people can't be trusted to have their consumer's best interests in mind.

Thanks for this. I should have looked at the YouTube description but it didn't occur to me to look there. This adds a good level of clarity, as does casey's answer.

Why is this any different than a house though? If you sell a house, you must get it inspected by a certified home inspector. After the sale closes, if you find anything wrong, too bad so sad, even if you find out by a load bearing beam crushing your skull.

@corsiKa Great question! Unfortunately, there does seem to be a difference. Not sure what exactly, but it is apparently expensive. I will add however, that finding overlooked mold in your attic or that the walls weren't insulated properly rarely leads to a spectacular crash and burn death and consequent lawsuit. Maybe that also has to do with the difference.

The USA has a culture of lawsuits, often frivolous.  When airplanes crash, people die and the estates of those people want someone to blame.  In the past they've tried to blame aircraft manufacturers and the resulting lawsuits were detrimental to general aviation.  It got to the point that congress had to step in and shield the industry from lawsuits (see: General Aviation Revitalization Act of 1994).
However, these protections don't apply to individuals.  Van's aircraft may get sued and if a judgement comes down the company will probably fold and cease to exist.  If you as an individual get slapped with a wrongful death lawsuit and a judgement is found against you, it will ruin you financially.  If you are getting to be old and retired, you may never recover from it.
The liability the builder shoulders is the accountability if anything ever goes wrong with the airplane, in perpetuity.  If that plane crashes some day and especially if it is fatal, someone is going see it is a homebuilt experimental and sue the guy who put it together, alleging they did something wrong.  It'll be expensive to lose and nearly as expensive to win (lawyers are not cheap).

I believe there is an expiration of 18 years to manufacturer liability, but not necessarily maintenance liability.

"Van's aircraft may get sued" They have been sued, see link in the question.

Just FYI I think you may have missed the point of the question, casey. It's understood that of course companies building and selling aircraft have liability.  I think the OP simply did not realise the builder in question wanted to donate the home-made aircraft.  Of course, then said builder would be liable.

@JoeBlow I don't think donation vs selling is a relevant difference when it comes to the liability the builder is exposed to.

Hi Casey, yes that's exactly what I mean.  I believe the OP very simply asked the question because the OP did not realise the person was trying to sell/donate the plane.  (note OP refers to "the builder/pilot".)

My father has built a small plane and talks about this problem (incidentally it is an RV through Van's too).
This is a very common understanding amongst the community involved in building RV's. When you sell a plane, you are incurring significant liability.
A point not really mentioned in the other answers is that it takes a certain type of person to build a plane. Many of those people are... let's say less than interested in someone else taking their money, especially through a lawsuit resulting from pilot error, which is probably immensely more likely than build defects.
Many homebuilders also are pretty financially well off, so they have a big target on their back in a litigious society.
Anecdotally I know of at least one RV that has an interesting post-flying life. It currently is hanging over an office space for a startup company as a very interesting and expensive decoration. The reason it is there, and not sold, is the same reason as the above.


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What could cause a distinct tube of condensation over a wing?
I recently saw something I've not previously encountered: shortly after take-off, for a few seconds, an extremely dense tube of condensation rose from about 75cm in front of the wing, in-board of the engine, to a height of about 50cm above the wing and then raced back over it.
The tube of condensation was exceptionally well-defined. It appeared to have a diameter of around 15-20cm, which hardly varied, and a very circular cross-section. Its surface was smooth, and it appeared and a few seconds later disappeared as abruptly as if controlled by a switch.
As an illustration of some of the airflow over that portion of the wing, it was quite remarkable - I expected it to be more turbulent than that.
What was the likely source of this well-defined condensation? It appeared to originate from below and in front of the wing.
I've seen condensation form and travel across portions of the wing many times before, but never in this fashion, so I was thrilled to see it.
The aircraft was a 767-300 if that makes any difference.

@GregHewgill Not a duplicate, that's a question about how condensation forms; this one is about its point of origin. It's answered below.

Also similar to the vortexes sometimes left behind the tips of wings or flaps.

If on a moist day you sit near the inlet of an MD-80, you can see a great condensation vortex going into the inlet from behind the Nose cowl, i.e. it is flowing aft to for and then does a 180 degree turn into the inlet. You can see it until ~50 knots.

What you might have seen is the condensation due to the vortex generated by the engine nacelle chine. The image below shows a vortex being generated by the chine.

Image from flickr.com. Photo credit- Frank Starmer

@aerolias That looked very much like what I saw, though what I saw recently was far thicker and denser, and better-defined. If it's coming off the leading edge of the strake/chine on the engine, that would explain a lot. I can't think of any other component around that area that would be responsible, so I will consider this the answer. The atmospheric conditions on the day must have been perfect for the formation of this vortex. Thanks!